[TheList] Aerials

Thu Feb 8 19:23:23 AEDT 2018

If the aerial is a mopole, then it depends on the frequency you want, 
the instructions come with the mopole.  If you have a groundplane to put 
a quarterwave on, then you do 75/freq.
IE ESA band is 75/75 = 1m, ESB is 75/145MHz (for example) = 517mm.

For scanners it's not so important, the importance comes with 
transmitting.  Is it a handheld scanner or a base scanner?  Given the 
lengths you've mentioned you've tried, I'll assume a base scanner.  You 
could try shortening one and you'll probably find it'll work 
sufficiently.   it also depends on where you are.. If you're a long way 
away from the repeater then you might find a yagi aerial will work 
better, but remember it's directional.

I have a 12 element UHF yagi pointing at Klondyke to receive Auckland 
Fire connected to a UHF T2020 series1.  I'm in a big dip in the middle 
of Hamilton city so it works.. just not well.  If it was higher than the 
hills around me, it'd work great.  However if I try listening to Waikato 
Rural police (which is on Sanitorium Hill/Ruru area) it's pretty 
average.. because the yagi isn't pointing in that direction.

Richard

On 08/02/18 21:14, Grant Carroll wrote:
>
> Dear all,
>
> This may seem a stupid question to some of you but I think it needs to 
> be asked - what is the optimum length for an aerial for a scanner 
> receiving VHF communications i.e. the ESA and ESB bands.
>
> Obviously, it needs to be longer than a UHF aerial but what is the 
> ideal length. I’ve used aerials of various lengths on my scanners and 
> with VHF I find the longer the aerial the worse the reception after 
> about two metres - in other words bigger is not better!
>
> But I’m sure there is someone on here who can tell me the perfect 
> length and the reason for it.
>
> Cheers and thanks for your help.
>
> Grunter1.
>
>
>
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